How Are Dental Implants Successfully Measured, And What Percentage of Dental Implants Are Successful?
Tagged: Medicine & Healthcare
1.0 Introduction
Dental implants are endosseous implants that have transformed the treatment of lost teeth during the previous three to four decades. Teeth loss, also known as edentulism, is fairly frequent in the elderly, when it is worsened by bone ridge loss and aesthetic issues. In the last several decades, advances in research and surgical procedures have made implant-supported prosthesis the first line of therapy and rehabilitation for edentulous individuals.
The prosthesis's success is dependent on the success of the dental implant. The list of parameters investigated for implant success is extensive and has had various additions since the 1960s, when this originally surfaced. Defining criteria has been difficult since this therapy requires a personalized approach to each case, based on patient history, comorbid illnesses, patient commitment, implant site, local circumstances, and other factors. The success of the implant is mostly down to osteointegration and biocompatibility. Because histological examinations are required for the optimal evaluation of osteointegration and biocompatibility, which is unfeasible, numerous non-invasive surrogate indicators are required to aid evaluate tissue responses.
Literature review
Albrektsson et al. analyzed available research in 1986 and developed success criteria for implants that were being utilized at the time. (1) It entailed a comprehensive and critical examination of scientific papers and conferences published between the late 1970s and the mid-1980s. The literature evaluation included studies from Europe, America, and Asia, and every effort was made to keep patients and implants on track for as long as feasible. The criteria established placed unprecedented emphasis on the bone reaction and the type of 'integration,' with bony integration being the most important indicator of success. Furthermore, the implant's features such as biological compatibility and surface, i.e. the contact with the bone bed, which influences the host reaction to the foreign material, were provided. Status of the site of implant, healthy uninfected and strong bone to hold the implant were host factors that were considered significant. Surgical technique and post-surgical undisturbed healing period were other criteria included. Finally, prosthesis-related factors like material, design, loading, patient care and patient satisfaction were also included. The review involved an unbiased approach to literature that used various implants and techniques and proposed a very practical approach to predict success. Criteria were based on a thorough understanding of the pathophysiology of the life of the implant under various existing treatment circumstances. It is no surprise that criteria proposed by Albrektsson were widely accepted and is still used in clinical practice. This paper also gave clear treatment recommendations based on their review and conclusions. They also outlined the need to meticulously record the events during the follow up of implants. They also highlighted that most studies were based on individual success rates and emphasized the need to have more controlled studies and data generation; all significant suggestions that guided future studies in this genre. The importance of the consumer knowing the long-term success rate based on longitudinal follow-up computed in the form of scientific data was also the need of the hour and it was emphasized in this review. To sum, this review was truly ahead of its times and succeeded in giving direction to future studies by giving objective criteria to measure success and hence facilitating comparison of study outcomes from various parts of the world.
Pjetursson et al presented a study of manual and electronic literature from 1966 to 2004 that evaluated survival and problems in tooth-supported vs implant-supported fixed dental prosthesis (FDPs) and single crowns. (2) Only patients with at least 5 years of follow-up were included, which is significant. The three electronic searches were well-designed, with explicit inclusion and exclusion criteria. To eliminate bias, the data was extracted by two independent reviewers, and standard criteria were utilized to describe survival, failure, success, and complications. The evaluation does, however, contain some single-center case cohort studies. To reduce this bias, data from many reconstructions from a single center were compared and analyzed. Furthermore, trials were not randomized, which gave rise to selection bias. The number of publications studying the various comparative groups were unequal ranging from 13 for cantilever FDPs to 26 for implant-supported FDPs. Only English language literature was reviewed, yet another source of selection bias. Poisson’s regression model was used to study complication and survival rates. The data was analysed and tabulated systematically. Survival, success rates were comparable for similar study groups and outliers were highlighted and critically analysed for reasons. Also, rates across methodologies were also compared from perspective of giving evidence-based management. However, follow up period of 5 years is considered less by several researchers and rightly so. Overall, this review is a good compilation and analyses of existing data, which gives clinicians a decent insight into techniques, complication, and success rates, with common causes for failure. But, as it included only patients from institutions, dentists from private practice were unable to relate to the findings summarised. Some of the shortcomings of implant related studies still existed in this review of literature as well, for e.g. uniform criteria and period of follow up especially for implant patients was still lacking. Also, various studies follow different success criteria and hence importance of reporting complication rate along with success rate for literature comparability was recognised.
Emami et al. conducted a meta-analysis in 2009 to compare the effect of implant-supported mandibular dentures to conventional dentures in terms of patient satisfaction, oral and general health, and quality of life. (4) Up to 2007, an electronic and manual search and evaluation of English and French literature was conducted. Only eight articles met the inclusion and exclusion criteria, and while implant-supported overdentures were more comfortable for patients, the study group was too small to produce any statistically meaningful findings. There was insufficient evidence to investigate the influence on overall health. One of the early investigations, however, attempted a comprehensive meta-analysis. It was necessary to do more research into the size of the influence of dental implants on patient outcomes.
Another review of literature undertaken by Eleman et al which analysed electronic literature was published in 2011. (5) Publications in English included retrospective and prospective studies comparing endodontic and implant treatment in between 1998 and 2008. At the end of selection, only 23 publications were reviewed, which is a low for comparing outcomes of different treatment approaches. Even then, most studies were retrospective and non-randomized without clear selection criteria, all potential sources of bias. The publications reported wide variations in the long-term success of the two groups, and this is understandable considering the bias in selection cited above. Also, contributing to this are the variety of factors that are responsible for the long-term success of implants. The review mentions several factors highlighted in different studies, albeit without definitive conclusive outcomes on the use of implants. So, it does not satisfactorily compare the two treatment modalities and cites the need for more research before making long-term success rates comparable.
A Malaysia based study published in 2015 by Alam MK and others evaluated patients’ satisfaction with implants using clinical and electromyographic studies. (6) This is a pilot study found in literature to use surface electromyography as a method to study outcomes in dental implant patients. Clinical success criteria were adapted from The International Congress of Oral Implantologists (ICOI) Pisa Consensus conference. Criteria for defining success were patient satisfaction-oriented, taking into consideration functionality and aesthetics along with morbidity related to the implant. This was a prospective randomised case control study involving 42 patients, where implants were placed between 2011 and 2013. Majority of those in the study were women amounting to selection bias. The study only included posterior implants with similar procedure and protocols used for management. Data was analysed using IBM SPSS Statistics with confidence level of 5%. This study could compare satisfaction, complication, success, and failure rates in a satisfactory manner as confounding factors were few. Patient satisfaction was assessed at different stages of treatment. However, long-term follow up with the similar or newly introduced criteria is required for this study to predict outcome and help in management decision making. Bias based on subjective perception of pain and aesthetic satisfaction by different subjects is bound to have some effect on the outcome. Study findings showed that patients were satisfied functionally and aesthetically with the procedure. Also, sEMG findings showed no significant difference between the control and study group.
Around the same period, Yao et colleagues conducted a literature study to better understand patients' expectations of dental implants. (7) This is consistent with the notion of evidence-based management, in which patients seek to be more active participants in their own care. An electronic search was used to find English literature, which was then assessed by two independent reviewers, and articles were chosen based on rigorous inclusion and exclusion criteria. The STROBE criteria (Strengthening the reporting of observational studies in epidemiology) were used to select articles, eliminating bias in selection criteria and inherent biases in research. Using patient expectations as a factor for dental implant success is a relatively new notion, with few research utilizing these criteria. Furthermore, the lack of standardised trustworthy and acceptable criteria makes meta-analysis difficult. Quantitative criteria e.g. Visual analogue scale (VAS) gave better understanding compared to qualitative criteria like ‘feeling of normalization’. Most studies included survival time, cost, functional and aesthetic satisfaction, special care requirement and source of their information in various formats. However, there was no way to compare any of these to give objective outcomes. This was the first attempt to review patient expectation as a measure of success and gave a narrative to summarize findings. However, there is need for more research and of globally accepted criteria for defining patient expectation and subsequent satisfaction. The biggest source of bias is the understanding by patients of the outcome of dental implants with respect to functionality, aesthetic value, life, cost, pain and treatment duration, additional care and effort needed, as this understanding will form the basis for patient satisfaction as an outcome of the procedure. Criteria to measure patient expectation are ambiguous and without standard definitions. The need of the hour is to set specific and sound definitions for patients’ expectation considering its complex nature and define globally accepted objective criteria and standardized instruments that can be used for meta-analysis.
A retrospective study was conducted by Da Silva and other practitioners engaged in applied research and learning network (PEARL) in general dental practice to study the outcome in non-institutionalised setting. (8) Patients from 87 practices and 920 implants were studied criteria for failure were clearly defined. The study showed failure rate of 18.7 %, with bone loss and periodontitis being the major factors for increase in the failure rate. This study was much needed as most data in literature was pertaining to institutions or academic organisations and private practice forms a major setting for dental procedures including implants. Though higher failure rate was recorded in the private setting, aesthetic outcome was found to be satisfactory. This study recorded only 3 to 5-year survival and long-term meticulous follow up is needed, which might be difficult in the private setting.
Conclusion
Most studies have a success rate of 95% to 98%, and with appropriate maintenance, implants can last a lifetime. However, success rates are affected by a variety of conditions and cannot be generalized. A systematic assessment of current research with strong methodology, impartiality, and meta-analysis should serve as the foundation for management procedures. In addition, success criteria for such investigations should be as objective and consistent as feasible. In compared to other types of therapy, the randomised case control study is the most effective paradigm for studying the efficacy of implants. The only standard outcome evaluated in all such trials should be the success rate free of problems represented as a percentage. Research on various implant materials, their active surface materials, surgical techniques, use of minimally invasive methods, use of adjuvants to enable healing/osteointegration, methods to reduce infection and marginal bone loss, are the need of the hour. This, combined with the fact that each implant is unique and dependent on comorbidity and habits, implant location, local conditions, implant characteristics, surgical technique, follow-up and patient motivation, and so on, highlights the need to study success and survival rates and the factors influencing them under each of these various circumstances.
References
1.Albrektsson T, Zarb G, Worthington P, Eriksson AR. The long-term efficacy of currently used dental implants: a review and proposed criteria of success. Int j oral maxillofac Implant [Internet]. 1986;1(1):11–25. Available from: https://www.researchgate.net/profile/George_Zarb/publication/19633876_The_long-term_efficacy_of_currently_used_dental_implants_A_review_and_proposed_criteria_of_success/links/56570d5008aeafc2aac0b605/The-long-term-efficacy-of-currently-used-dental-implants-A-review-and-proposed-criteria-of-success.pdf
2.Pjetursson BE, B. U. (2007). Comparison of survival and complication rates of tooth-supported fixed dental prostheses (FDPs) and implant-supported FDPs and single crowns (SCs). Clinical Oral Implant Research, 97-113.
3.Pjetursson BE, Karoussis I Burgin W, Bragger U, Lang NP. Patients’satisfaction following implant therapy. A 10-year prospective cohort study. Clin Oral Implants Res 2005 Apr;16(2): 185-93.
4.Emami E, Heydecke G, Rompré PH, de Grandmont P, Feine JS. Impact of implant support for mandibular dentures on satisfaction, oral and general health-related quality of life: a meta-analysis of randomized-controlled trials. Clin Oral Implants Res. 2009;20(6):533‐544. doi:10.1111/j.1600-0501.2008.01693.
5.Elemam RF, P. I. (2011). Comparison of the Success Rate of Endodontic Treatment and Implant Treatment . International Scholarly Research Network Dentistry, 1-8.
6.Alam MK, Rahaman SA, Basri R, Sing Yi TT, Si-Jie JW, Saha S (2015) Dental Implants – Perceiving Patients’ Satisfaction in Relation to Clinical and Electromyography Study on Implant Patients. PLoS ONE 10(10): e0140438. doi:10.1371/journal. pone.0140438.
7.Yao, J., Tang, H., Gao, X. L., McGrath, C., & Mattheos, N. (2014). Patients' expectations to dental implant: a systematic review of the literature. Health and quality of life outcomes, 12, 153. https://doi.org/10.1186/s12955-014-0153-9.
8.Da Silva, J. D., Kazimiroff, J., Papas, A., Curro, F. A., Thompson, V. P., Vena, D. A., Wu, H., Collie, D., Craig, R. G., & Practitioners Engaged in Applied Research and Learning (PEARL) Network Group (2014). Outcomes of implants and restorations placed in general dental practices: a retrospective study by the Practitioners Engaged in Applied Research and Learning (PEARL) Network. Journal of the American Dental Association (1939), 145(7), 704–713. https://doi.org/10.14219/jada.2014.27
